MATLAB Function Reference (Volume 2: Graphics)

uicontextmenu Propertiesdefines a default value on the root level that sets the figure IntegerHandleproperty to off whenever you create a uicontextmenu object. MATLABexecutes this routine after setting all property values for the uicontextmenu.Setting this property on an existing uicontextmenu object has no effect.The handle of the object whose CreateFcn is being executed is accessible onlythrough the root CallbackObject property, which can be queried using gcbo.DeleteFcnstringDelete uicontextmenu callback routine. A callback routine that executes whenyou delete the uicontextmenu object (e.g., when you issue a delete commandor clear the figure containing the uicontextmenu). MATLAB executes theroutine before destroying the object’s properties so these values are availableto the callback routine.The handle of the object whose DeleteFcn is being executed is accessible onlythrough the root CallbackObject property, which you can query using gcbo.HandleVisibility{on} | callback | offControl access to object’s handle by command-line users and GUIs. Thisproperty determines when an object’s handle is visible in its parent’s list ofchildren. HandleVisibility is useful for preventing command-line users fromaccidentally drawing into or deleting a figure that contains only user interfacedevices (such as a dialog box).Handles are always visible when HandleVisibility is on.Setting HandleVisibility to callback causes handles to be visible fromwithin callback routines or functions invoked by callback routines, but not fromwithin functions invoked from the command line. This provides a means toprotect GUIs from command-line users, while allowing callback routines tohave complete access to object handles.Setting HandleVisibility to off makes handles invisible at all times. Thismay be necessary when a callback routine invokes a function that mightpotentially damage the GUI (such as evaluating a user-typed string), and sotemporarily hides its own handles during the execution of that function.When a handle is not visible in its parent’s list of children, it cannot be returnedby functions that obtain handles by searching the object hierarchy or queryinghandle properties. This includes get, findobj, gca, gcf, gco, newplot, cla, clf,and close.2-531